How to flush sealed central heating system

[zanwan]

I have a Saunier Duval f30e classic and am thinking of flushing the central heating system.

I've never flushed a central heated system before (have refilled a couple after adding rads).

Has anyone got any tips, do i use Flush, how long do i leave the CH cleaner in the system before flushig?

 

[jackpike]

my method, some will disagree but its cheap and effective,
take off a small radiator, preferably near a door downstairs, connect hosepipes to each valve, i use 3/4 flexi's connected to speedfit pipe, open the valves and take the hoses to a drain, shut the boiler flow and return valves and all the rad valves to each rad, open the filling loop, this is now flushing the return pipe (assuming thats what the filling loop is on ). give it 10 minutes then close the hosepipe valve that was running, open the boiler valves and now you are flushing the flow. give that 10 minutes, next open one rad and flush that 10 minutes, then close that rad and flush another, and so on till all the rads are flushed,
add x100 when finished and you have a clean system without all the mumbo jumbo jet wash hype and costly chemicals,

 

[ChrisR]

C'mon Tom we can't earn £100k a year if you bypass the mumbo jumbo, we'll be down to 20k!

Yeah I do something similar but - the boiler valves are likely to leak, so just shut one, it halves the risk..

With all the valves shut you'd expect no flow at all one side at the beginning.
If you empty one rad you can use it as a pressure accumulator, to blast water out when you open the valves on one of the other rads.

Working out where the flows and returns are, can be fun!

 

[zanwan]

Whats the science behind having to flush an individual rad at a time? I would have thought you could open them all up, open the drain vale, attach hose, and then open the filling loop to keep the water flowing through the system, flushing it out?

 

[D_Hailsham]

What's the science behind having to flush an individual rad at a time? I would have thought you could open them all up, open the drain vale, attach hose, and then open the filling loop to keep the water flowing through the system, flushing it out?

If you open all rad valves, including the LS valves, there is no guarantee that the water will flow through every rad. It will always take the easiest path with the lowest resistance. So rads nearer to the hose connection points will get more favourable treatment. Doing one rad a a time means they all get equal treatment.

shut the boiler flow and return valves

What if the boiler does not have flow and return valves?

 

[Boilerman2]

If no valves you cut & plug off the Heating flow & Return BUT as the OP stated that he has a SD F30 , then it is irrelevent as there are valves!!

 

[Agile]

Naz, you flush each rad individually so that the entire flow goes through that rad and maximises the flow rate.

Tony

 

[Happyplumber]

Go onto the kamco website and it will have full instructions on how to flush a system,if you dont have machine then do this with a house pipe under mains pressure,each individual rad has to be done and the process is long and laborious

A proper powerflush machine with a heater and magnetic filter will clean the system beautifully,there are advocates of removing rads going in the garden and all sorts of nonsense but the professionals will use flushing machines and decent quality chemicals, personal favourite is FX2 or X800 and sentinel X100 inhibitor

If you want to see the results of system which has not had the system cleansed properly then go onto my profile and have look at Heatline photos unfortunately this boiler had to be scrapped because the main heat exchanger being ginnoni with very tight clearances was totally blocked with magnetite

 

[zanwan]

Go onto the kamco website and it will have full instructions on how to flush a system,if you dont have machine then do this with a house pipe under mains pressure,each individual rad has to be done and the process is long and laborious

A proper powerflush machine with a heater and magnetic filter will clean the system beautifully,there are advocates of removing rads going in the garden and all sorts of nonsense but the professionals will use flushing machines and decent quality chemicals, personal favourite is FX2 or X800 and sentinel X100 inhibitor

If you want to see the results of system which has not had the system cleansed properly then go onto my profile and have look at Heatline photos unfortunately this boiler had to be scrapped because the main heat exchanger being ginnoni with very tight clearances was totally blocked with magnetite

blimey just hada look at those pics, that looks like an aweful blockgae! so i assume that was caused by a poorly done cleaning job?

 

[Happyplumber]

It was a conventional open vent system converted to sealed combination boiler,done on the cheap by polish builders without any kind of cleaning .The thing lasted for 6 months and then time for new boiler.Do it cheap do it twice .I dont mind when i went in there had to clean complete system run new gas pipe move the boiler from their location to correct one and supply n fit new

 

[CrazeUK]

I have read a few things, and no one seems to mention flushing the pipes?
Is it not required? Also how do you figure out which is connected to which?

Also i read a step by step walk through using a flushing machine, and it says to connect the machine at one radiators pipes (i.e. the bathroom)
Then turn all the rads off, and open the valves 1 by 1.

I understand the concept.. BUT dont you then risk pumping sludge through the entire system, AND through the boiler?